<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      * {
        padding: 0;
        margin: 0;
      }
      .father {
        box-sizing: border-box;
        width: 80vw;
        height: 80vh;
        border: 10px solid pink;
        border-radius: 50px;
        /* 父相 - 相对定位 */
        position: relative;
        left: 10vw;
        top: 10vh;
      }
      .first {
        width: 30vw;
        height: 30vh;
        background-color: orange;
        /* 子绝 - 绝对定位 */
        position: absolute;
        left: 15vw;
        top: 15vh;
        z-index: 1;
      }
      .second {
        width: 40vw;
        height: 40vh;
        background-color: green;
        position: absolute;
        left: 35vw;
        top: 35vh;
      }
      .third {
        width: 10vw;
        height: 10vh;
        background-color: rgb(76, 153, 255);
        position: absolute;
        left: -5vw;
        top: -5vh;
      }
    </style>
  </head>
  <body>
    <div class="father">
      <div class="first"></div>
      <div class="second"></div>
      <div class="third"></div>
    </div>
  </body>
</html>
